That's not bad, without doing a total tear apart I can see a LOT of work has gone into it, not so much the actual labor but whoever did it took care in ensuring it was built right, so to speak.

The images appear optimized, the code looks neat and clean, I mean, like I said, without running it through some analyzer, it's one of the better ones out there.

I particularly like how your payment page is asp (which I guess it has to be due to SSL) but again the programmer was smart enough to understand that asp consumes server resources and thus built the rest of the pages in html which, from the look of things, appears to conform to a standard as well.